Compositions for cleaning machinery and electrical equipment



United States Patent I h ce fliilfil l Fatented Jan. 2%, 1%65 3 167,514CDMPOSlTlONS FGll CLEANING MACHENERY AND ELECTRECAL EQUWMENT Hayward R.Baker, Silver Spring, lVliL, assignor to the United States of America asrepresented by the Secretary of the Navy No Drawing. Filed Mar. 7, 1962,Ser. No. 178,21lll 3 Claims. (Cl. 252-170) (Granted under Title 35, US.Code (1952), see. 265) The invention described herein may bemanufactured and used by or for the Government of the United States ofAmerica for governmental purposes without the pa merit of any royaltiesthereon or therefor.

This application is a continuation-in-part of application Serial No.821,333, filed June 18, 1959, for Compositions for Cleaning Machineryand Electrical Equipment, now abandoned.

This invention relates to cleaning compositions for removing oily orgreasy contaminations, more particularly to organic compositions whichare used as aqueous emulsions for displacing any sort of contaminationadhering to machinery, electronic equipment, electric motors and thelike.

In the past, aliphatic hydrocarbon solvents that were found useful inoil cleaners or degreasers had relatively low flash points of about 104F., and such cleaners required the inclusion of certain halogenatedhydrocarbon snuifers to reduce fire hazards and to provide increasedcleaning power. Chlorinated hydrocarbons, such as dichloroethylene,chloroform, 1,1,l-trichloroethane, which were blended with volatilehydrocarbons for this purpose, have been found to be considerably toxicto workers, as well as corrosive to metals and often detrimental toinsulating materials, painted surfaces, resins, plastics, etc.

New and useful compositions have now been formulated in accordance withthe present invention which are more effective in removing oily andgreasy contaminations from metals and other surfaces and whichaccomplish this end without the presence therein of any chlorinated orother halogenated compounds. Moreover, said compositions have been foundto be substantially non-corrosive to metal parts, less injurious toinsulating materials and substantially non-toxic to the workers.

It is therefore an object of the present invention to provide organiccompositions which can be readily formed into cleaning emulsions forremoving oily, greasy, adherent contamination from metal surfaces andfrom electrical equipment.

Another object of the invention is to provide novel cleaning emulsionswhich are highly effective for rupturing oil and grease films andwashing away the contaminant material with substantially no mechanicaltreatment of the surfaces and with considerable savings in time andlabor.

A further object of the invention is to provide compositions which areeffective in dislodging and washing away adherent lubricants, fuel oils,debris and other coatings, short of dried paint, resins, plastics, etc.

A still further object of this invention is to provide cleaningcompositions which are safer to use than previous cleaners for oils andgreases in that they do not create fire hazards, are not irritant to theskin and do not adversely affect the cleaned parts.

According to the present invention, organic compositions are formulatedwhich can be readily formed into cleaning emulsions capable of breakingor rupturing adherent oil and grease films. The aqueous emulsions, whichare formed at the time of use, are very effective for removing oils,greases, waxes, fats, paint vehicles and thinners, in fact,substantially all adherent films or coatings, except for permanentpaint, plastic and resinous coatings. The emulsions formed by means ofthe present organic compositions provide rapid, easy and completeremoval of such contaminants by applying said emulsions in anyconvenient manner, for example, by pouring onto the contaminant surface,by spraying a light stream of emulsion, or by supersonic agitation in acleaning tank. Once the cleaner emulsion contacts the contaminant filmon a surface, the film is ruptured and pushed back exposing a bare,clean surface; the contamination is rendered non-wetting and it iseasily flushed away with additional cleaner or with flushing Water withno recontamination of surfaces over which it is flushed.

The organic composition which provides the cleaner concentrate of theinvention consists essentially of (l) a liquid aliphatic hydrocarbonhaving a flash point of about 140 F., (2) a surfactant or surface activeagent of the non-ionic type and of high adsorptive power, and (3) apenetrant which is an oily additive capable of dissolving into andcombining with contaminant materials.

The organic composition is now described in greater detail, and the roleof each ingredient in the emulsion cleaner is presented in the followingspecific description.

(1) The present invention provides a liquid aliphatic hydrocarbon whichhas a hash point of about 140 F. with a boiling range which may extendfrom about 350 F. to about 450 F. The aliphatic hydrocarbon componentmay comprise mineral spirits. More specifically, a solvent suitable forthis purpose is known as the Dry Cleaning Solvent, Type II, or aliphaticnaphtha. The Amsco 140 solvent which is supplied by the Americanlviineral Spirits Company is essentially an aliphatic hydrocarbon with aclose-cut boiling range and possessing a mild odor.

he Initial Boiling Point of this fraction is 364 F, while the fractionthereof has a boiling point as high as 387 F. The flash pointdetermination of this fraction averages about 142 F.

in an oil-in-water emulsion, an aliphatic hydrocarbon solvent with aflash point of about 140 F. is less harmful to electrical insulationthan with aromatic constituents or with those containing chlorinatedhydrocarbons. It is also desirable to employ a higher flash pointsolvent than the conventional type cleaners naphtha (of about -104 F.),since a higher flash point solvent obviates the need for any chlorinatedhydrocarbon snuffer or other similar components to suppress thecombustible nature of solvents. A dash point of'about F. for thesolvent, specified in the present invention, has been found to be higherthan the flash point of most contaminants with which it comes incontact.

(2) In accordance with the invention, a small amount of surfactant orsurface active agent is included in the composition to provide thenecessary adsorptive power for breaking and displacing an oily typefilm. The term surfactant is used in the present specification toindicate a surface active agent, which in conjunction with an aliphaticsolvent, has been found to be capable of displacing an oil fromcontaminated surfaces. This oildisplacing effectiveness is observed whena drop of cleaning emulsion containing a specific surface active agentis placed on an oil film. The maximum area from which the cleaningemulsion clears away the oil to expose a bare surface is taken as anindication of the oil-displacing ability of that surface active agent.

A surface active agent is needed to hold the hydrocarbon in a usefulemulsion with water. Therefore, an effective surfactant for use in thepresent compositions keep the solvent dispersed in an oil-in-wateremulsion as well as provides for the complete displacement of oil fromcontaminated surfaces.

in accordance with the invention, effective oil-displacing andwater-emulsifying surface active agents are provided by suchcommercially available surfactants as Span- 85, Nonisol-i00, TergitolNonionic NPX, Pluronic, and Triton Xl55. These surfactants are of thenon-ionic type that can be used effectively in emulsions with eitherfresh or salt Water. Effective non-ionic type surfactants are providedby polyglycol esters of the fatty acids and by polyoxyalkylenederivatives. For example, polyethylene glycol 400 monooleate has beenfound to be a particularly effective compound for this purpose. Thepolyethylene glycol ester of lauric acid, sold as Nonisol 100 by GeigyChemical Corp, is a further example of a polyglycol ester which forms aneffective surfactant for the present cleaning compositions. Condensatesof ethylene oxide with a hydrophobic base are formed by condensingpropylene oxide with propylene glycol (Pluronics). The effectivesurfactant in accordance with the invention containing the ethyleneoxide in an amount in the range of between in about to 30% by weight ofthe product. The surfactants listed above are included in SurfactantsListed by John W. McCutcheson, published in 195 8, said publicationbeing a reprint from Soap & Chemical Specialties, December 1957,.lanuary, February, March and April 1958. The Nonisol 100 is describedin said publication as a polyethylene glycol of lauric acid in which thepolyethylene glycol has an average molecular weight of 400. ThePluronics are identified in said publication as condensation products ofethylene oxide with a hydrophobic base which is formed by condensingpropylene oxide with propylene glycol.

in simulated tests, emulsions containing 0.25% of polyethylene glycolmonooleate provide superior cleaning compositions possessing highcutting and displacing power of oil films, as measured by area sizeexposed when oil films were acted upon by drops of cleaning emulsion.

The polyethylene glycol monooleate which has been used in the presentcleaning compositions has an average polyethylene glycol molecularWeight of between 300 and 600, and the final esterified product isdesignated as polyethylene glycol 400 monooleate. In addition to itsadsorptive power this material is a good rust inhibitor and affordsprotection to the clean surface during the cleaning operation and alsoafter the surface has dried by means of a very fine film of themonooleate that remains on the cleaned surface.

A desirable surfactant keeps the solvent mixture dispersed in anoil-in-water emulsion only until the solvent droplets touch the surfaceof the contaminating film. Non-ionic type surfactants which have beenfound useful for the present invention are included in the organicsolvent mixtures in an amount of about 1 percent or less by weight inorder to provide an unstable emulsion which remains dispersed until theemulsion contacts the film surface. Upon contact, the solvent isimmediately released to break and push back the oil film. The preferredconcentration of surfactant is in the range of about 0.5 to about 1.0percent by Weight of the organic mixture, while a concentration in theorder of 0.2 percent or less causes the emulsion mixture to break toorapidly and becomes diificult to use as a light spray.

y (3) Emulsions containing only aliphatic naphtha and a surfactant areable to push back a contaminant film only after the film has beenruptured by strong spray impact to put emulsion droplets in contact withbare surface. In accordance with the invention, a blending agent orpenetrant is included in the cleaning composition which is capable ofpenetrating the' contaminant film and blending with it, enabling thesolvent and surfactant to reach the underlying surface. The ability ofthe penetrant to blend with a contaminant film depends upon its surfacetension which should have a value intermediate between the surfacetension of the solvent and that of the contaminant film. The solventhas. a surface tension of less than dynes/ cm. While an adherent oilyfilm has a surface tension nearly dynes/cm. or more. The solvent cannotdissolve an oily film readily, but the presence of a blending agent orpenetrant with a substantially higher surface tension than that of thesolvent and closer to the surface tension of adhering oily films iscapable of promoting rapid penetration of oily films.

The inclusion of a petroleum hydrocarbon having physical propertiessubstantially within the following indicated ranges, materially affectsthe performance of the present cleaning emulsions and adapts them to thedisplacement of many contaminant films having surface tensions from26-3Z dynes/cm'at 25 C.

DI S'IILLATION Fraction: Boiling range, F. 10% 425 to 500 50% 490 to 530665 to710 End point 715 to 750 PROPERTIES OF THE PENETRANT COMPONENTViscosity F. 2.0 to 6.0 centistokes.

Flash point to 250 F. Pour point Less than0 F.

romatic content 10 to 25 Surface tension 27.0 to 30.0 dynes/cm. 25C.

A turbojet lubricating oil, Grade 1005, used on jet engines andconforming to specification, MilO-6081B, has been found to be aneffective penetrant that promotes rapid penetration of oily films. Also,a diesel fuel oil, Type I, designed for engine speeds over 1000 rpm. andwhich meets specification, Mil-F-16884C is characterized as a distillateengine oil with no cracking materials therein, but one that may containcertain suitable additives to improve the performance of the oil. Theoil provides substantial penetration into adherent films when it is usedas a penetrant in the present emulsion cleaners.

The physical properties of said penetrants are listed in the tablebelow:

h Jet engine Diesel Oil Distillation lubricant (Mil-F- (Mil-O- 168840)486 426 527 495 90%-- 706 668 End point 747 718 Viscosity 100" I 5. 6 4.8 Flash point F" 232 158 Four point F. 65 40 Aromatic content...-.percent. 17 12 Surface tension... .....dynes/cm. 25 0.. 28.0 27. 6

The oil penetrants mentioned above have great penetrating power, arecapable of promoting the dissolution of almost any oily contaminant andmay be used against fuel oils, diesel oils, parafiins, gear oils,diesters, polyesters, polychlorophenyls, polypropylene oxides, siliconeoils, fluorocarbons, heavy grease materials and asphaltic residues. 1

The cleaning compositions are normally mixed with about an equal volumeofwater in forming emulsions,

although the organic mixture form s useful emulsions in concentrationsof between about 5-60 percent by volume. Low concentrations of organicmixture have been found useful forcleaning :salt water residues. Theemulsion mixturesare effective with either fresh or sea water. Cleaningemulsions are formed with lesser amounts of sea Water. It will beappreciated that sea water emulsions necessitate a fresh water rinse toprevent salt deposition on the cleaned surfaces. are formed by simplyagitating the organic composition mixture with the water layer. Theemulsions are not toxic or irritating to the skin and the fire hazard isconsiderably minimized so that no special handling of the emulsions isnecessary. r a i The emulsions The organic composition of the presentinvention may be varied within the following ranges.

Component: Percent by weight Aliphatic hydrocarbon, flash point 140 F.89.5 to 96.5 Penetrant 3 to Surfacant 0.3 to 1 The invention is furtherillustrated by the following Nonisol X-100 Water (percent by vol.)

Example III Component: Percent by weight Aliphatic hydrocarbon, flashpoint 140 F. 89.5

Turbojet lubricating oil, Grade 1005 10 Polyethylene glycol 400monooleate 0.5 Sea water (percent by vol.) 20

The composition may be used as a spray cleaner, the solvent mixture ismechanically mixed with water in any convenient manner and the emulsionis sprayed on contaminated surfaces at pressures of about 20 to 80 psi.A spray gun at a pressure of about 80 psi. assists in the penetration,dispersion and removal of all traces of dirt and oil films withoutinjury to the most delicate insulating materials or electronic devices,even at nozzle-tosurface distances of only a few inches.

Mobile electrical and mechanical structures may be subjected toultrasonic radiation while immersed in the bath of the cleaningemulsion. The increased agitation drives the cleaning emulsion intorecesses of motor parts that are inaccessible by other means.

Following the spray or immersion step, the treated parts are flushedthoroughly with water, either by spraying means or by ultrasonictreatment, to remove all cleaning emulsion and traces of oilycontamination and dirt. The cleaned parts are then air-dried, preferablyby directed streams of compressed air. For further complete drying theparts may be blown with heated air.

The invention, therefore, discloses cleaning compositions which are botheconomical and safe to use, that effectively remove oily and greasycontaminants without scrubbing or rubbing oily films and that areeffective in cleaning machinery and electrical equipment by applying thecleaning emulsions to an oily contaminant and flushing away the loosenedcontamination.

Obviously many modifications and variations of the invention may be madewithout departing from the spirit and scope thereof, and therefore, onlysuch limitations should be imposed as are indicated in the appendedclaims.

What is claimed is:

1. An organic composition which forms an aqueous cleaning emulsion, saidcomposition consisting essentially of 89.5 to 96.5 percent by weight ofan aliphatic hydrocarbon having a minimum flash point of about 140 F.,of 3 to 10 percent by weight of a penetrant oil from the group of oilsconsisting of diesel oil and light lubricating oil, said oils having asurface tension of between about 27 to 30 dynes/cm. 25 C. and of 0.5 to1 percent by weight of polyethylene glycol monooleate having an averagepolyethylene molecular weight of about 300 to 600.

2. An organic composition which forms an aqueous cleaning emulsion, saidcomposition consisting essentially of 89.5 to 96.5 percent by weight ofan aliphatic hydrocarbon having a minimum flash point of about 140 F.,of 3 to 10 percent by weight of a penetrant oil which is a diesel oilhaving a surface tension of about 27.6 dynes/cm. 25 C., and of 0.5 to 1percent by weight of polyethylene glycol monooleate having an averagepolyethylene molecular weight of about 300 to 600.

3. An organic composition which forms an aqueous cleaning emulsion, saidcomposition consisting essentially of 89.5 to 96.5 percent by weight ofan aliphatic hydrocarbon having a minimum flash point of about 140 F.,of 3 to 10 percent by weight of a penetrant oil which is a lightlubricating oil having a surface tension of about 28.0 dynes/cm. 25 C.and of 0.5 to 1 percent by wei ht of polyethylene glycol monooleatehaving an average polyethylene molecular weight of about 300 to 600.

References (Iited by the Examiner UNITED STATES PATENTS 2,208,524 7/40Darsey et a1 1486.15 2,613,186 10/52 Pickett et al. 252l 2,866,726 12/58Vance 252171 X OTHER REFERENCES Bennett: The Chemical Formulary; vol. 1(1933), page 153.

Goldsmith: Chemical Industries; March 1943, pages 327-8. JULIUSGREENWALD, Primary Examiner.

JOSEPH R. LiBERMAN, ALBERT T. MEYERS,

Examiners.

1. AN ORGANIC COMPOSITION WHICH FORMS AN AQUEOUS CLEANING EMULSION, SAIDCOMPOSITION CONSISTING ESSENTIALLY OF 89.5 TO 96.5 PERCENT BY WEIGHT OFAN ALIAPHATIC HYDROCARBON HAVING A MINIMUM FLASH POINT OF ABOUT 140*F.,OF 3 TO 10 PERCENT BY WEIGHT OF A PENETRANT OIL FROM THE GROUP OF OILSCONSISTING OF DIESEL OIL AND LIGHT LUBRICATING OIL, SAID OILS HAVING ASURFACE TENSION OF BETWEEN ABOUT 27 TO 30 DYNES/CM. @ 25*C. AND 0.5 TO 1PERCENT BY WEIGHT OF POLYETHYLENE GLYCOL MONOOLEATE HAVING AN AVERAGEPOLYETHYLENE MOLECULAR WEIGHT OF ABOUT 300 TO 600.